The orthonormal condition is [1]},
\(\int _{-1}^{1} d \cos \theta \, {}_{-2} S_{\widetilde{l} \widetilde{m}}(\theta )\, {}_{-2}S_{\widetilde{l}^{\prime } \widetilde{m}}(\theta ) = \delta _{\widetilde{l} \widetilde{l}^{\prime }}.\) 
